Tandem propeller



Oct. 10, 1950 E. w. MORRIS TANDEM PROPELLER 2 Sheets-Sheet 1 Original Filed Sept. 10, 1958 N N m %N I QM. WN\ W0 m w .m W L M w I M MM i Q l 1|..L N \f i 3 x f E *4 EN & E W 9 Q ww um u/ wwm Q Q 9w MN fiOH H ATTORNEY Oct. 10, 1950 E. w. MORRIS TANDEM PROPELLER 2 Sheets-Sheet 2 Original Filed Sept. 10, 1938 ATTORNEY Patented Oct. 10, 1950 TANDEM PROPELLER Edward W. Morris, dece N. J., by Martha W.

Dayton, Ohio, assignor I poration, a corporation of Delaware Continuation of September 10,

1944, Serial No. 538,995

This invention relates to improvements in aeronautical propellers and comprises a controllable pitch propeller hub mechanism by which a clear hollow passage is left in the propeller shaft in order to accommodate a gun or cannon, or by which propellers may be mounted in tandem relationship for opposite rotation. In connection with the latter use of the invention, it should be noted that present types of commercially available controllable pitch propellers utilize blade pitch changing mechanisms which are concentric with the propeller and which form obstructions to the insertion of a through-hollow shaft such as a gun barrel or a secondary propeller shaft.

An object of the invention is to provide a multiblade controllable pitch propeller having multiple power units between the blades and adjacent the hub thereof which are geared together to afford a blade pitch changing mechanism. A further object is to provide tandem controllable pitch propellers each propeller of the pair having its own pitch changing mechanism. Still another object is to provide a tandem controllable pitch propeller organization in'which a clear axial passage is left through the innermostpropeller shaft. Still another object is to provide means by'which power for blade pitch changing may be transmitted from a casing to each of two tandem arranged controllable pitch propellers.

Further objects and advantages of the invention will become apparent in connection with a reading of the annexed detailed description in connection with the drawings, in which:

Fig. l is a longitudinal section through a pair of tandem propellers and the pitch changing mechanism thereof, and

Fig. 2 is a section on the line 2--2 of Fig. 1.

This application is a continuation of application SerialNo. 229,275, filed September 10, 1938, now abandoned.

In a broad sense, this invention comprises improvements over the invention described in Patent No. 1,951,320, in the name of W. J. Blanchard, issued March 13, 1934.

In said patent is shown and described a con trollable pitch propeller carrying an electric motor and reduction gearing ahead of and coaxial with the propeller, the gearing being connected to the propeller blades to effect pitch changes thereof. Propellers covered by the Blanchard patent have gone into extensive use but certain demands have been made which call for improvements in the pitch changing arrangement to allow for the use of tandem propellers on the airplane and also to allow of the insertion 18 Claims. (Cl. 170-13524) propeller blades l5 are mounted ased, late of Rutherford,

Morris, administratrix, to Curtiss-Wright Corapplication Serial No. 229,275, 1938. This applicationJune 6,

2 of a gun barrel through the propeller shaft. Re ferring to Fig. 1, it will be seen that two concentric propeller shafts l0 and H extend from the nose of a power plant such as l2. Upon the outer and shorter propeller shaft I0 is splined a propeller hub l3. secured by a nut l4 and the hub on bearings I6 for pitch changing rotation. Secured to the front of the hub I3 is a gear cover later to be described and a housing l1, the latter providing a socket for a pilot ball bearing l8 which supports the smaller propeller shaft II, the inner race of the bearing being clamped against asplit shoulder is set into a groove in the shaft H by means of a lock nut 20 screwedon the shaft. Against the forward face of the nut and surrounding the shaft is a tapered centering ring 20' for the forward propeller hub 2|. The hub 2| carries propeller blades 22 in bearings 23, said hub being retained upon the shaft II by a propeller hub nut 24. Both hubs l3 and 2| are splined to respective propeller shafts as at 26 and 21.

As shown, both propellers carry three blades although the number of blades of the propellers is immaterial so faras the scope of the invention is concerned. Between the hub sockets as shown in Fig. 2 are located electric motors 28 each operating through an epicyclic speed reducer 29 concentric with the motor to drive pinions 30, each of the pinions 30 engaging sectors 32 integral with a hub 33 s lined to the hub 34 of a bevel gear 35 which engages bevel gears 36 mounted on the buttsof respective propeller blades IS. The gear hub 33 with the elements 34 and 35 are, as shown, concentric with the propeller shaft. As will be noted in Fig. 2, the space between the several gear sectors 32 allows of the passage of lugs of the housing [1 by which the housing may be attached to the hub l3 by bolts indicated at 38. The several gear sectors 32 and pinions 30 are covered as shown by a suitable housing 40 clamped between the housing I! and the hub I3.

The detailed mechanism for effecting pitch changes in the propeller blades 22 is identical with that just described, numbers of parts in the forward propeller installation corresponding to the numbers of similar parts in the rear propeller installation.

By the use of the circumferentially spaced motor and speed reducer units 28, 29, on both the rear and forward propellers of the tandem pair, the propeller shaft l I and forward propeller may be made hollow as shown providing a clear passage which may be utilized in any appropriate manner such as for the location of a gun barrel.

If there is no need for the use of a through, hollow shaft, it is apparent that the forward propeller might be replaced by one of a conventional type having a concentric motor and speed reducer while the rearward propeller with its circumferentially spaced motors and speed reducers allows of the installation of the forward propeller in tandem.

At 44, is indicated a plurality of slip rings with which a plurality of electrical contactors 45 fixed to the casing I 2 engage. Certain of the slip rings 34 are connected through cables, one of which is indicated at 46, to provide selective forward or reverse operation of the several motors 28 of the rear propeller. Others of the slip rings 44 are connected by conductors, not shown, to contact holders 48 carried by the housing I! of the rear propeller, the contact elements contained in the holders 48 engaging slip rings 50 mounted upon the hub 2| of the forward propeller connected by suitable conductors to the several motors 28 of the forward propeller for selective forward or reverse operation thereof. The central electrical connections for a system of the character here disclosed are similar in principle to those indicated in said Blanchard patent, and are deemed to be well-known to those familiar in the art, and accordingly, are not shown in detail. Suffice it to say, that by selective forward or reverse actuation of the motors 28 of either propeller, the pitch of the blades of respective propellers may be increased or decreased.

The use of tandem propellers as such is known to be old in the art, and their use compensates for the effect of propeller torque on the airplane improving controllability of the latter. Their use also minimizes gyroscopic effects of the propeller system on the airplane and virtually eliminates the spiral slipstream normally occurring in the wake of a single propeller. A pair of two or three blade tandem propellers is superior to a single propeller having a large number of blades, and, in single engine aircraft, tandem propellers may be used with good high speed efflciency, and

their diameter may be less than that of a single propeller, affording better ground clearance and minimizin the height of the landing gear of the plane. Since controllable pitch propellers have been accepted as a necessary adjunct to modern high performance aircraft, this invention makes available a practicable solution for the propeller installation on high power engines and provides tandem controllable pitch propellers of practical type and form, utilizing well-known mechanical principles and providing means for effecting propeller pitch control.

While there is shown and described herein certain structure embodying the invention, it will be obvious to those skilled in the art, after understanding the invention, that various changes and modifications may be made therein without departing from the spirit or scope of the invention. The appended claims are intended to cover all such modifications and changes.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is: N

1. In an aircraft propeller, a hub having blade sockets, blades journalled therein for pitch change having bevel gears at the butts thereof, a gear concentric with the hub drivably engaging said butt gears, power transmission units equal in number to the number of blades and disposed on said hub in the blade plane and between said blades and spaced from the hub axis,

a driving connection from each said power transmission unit to said concentric gear, and motor means driving said power transmission units.

2. In a controllable pitch propeller, a shaft having a hub secured thereto the hub including blade sockets having blades journalled therein for pitch change, a bevel gear sector on each blade butt, a bevel, gear concentric with the hub engaging said gear sectors, a spur gear concentric with and secured to said bevel gear, power transmission units secured to the hub between said blade sockets each having a driving pinion engaging said spur gear, and motor means driving said power transmission units.

3. In a controllable pitch propeller, a shaft having a hub secured thereto the hub including blade sockets having blades journalled therein for pitch change, a bevel gear sector on each blade butt, a bevel gear concentric with the hub engaging said gear sectors, a spur gear concentric with and secured to said bevel gear, and power units secured to the hub between said blade sockets each having a driving pinion engaging said spur gear, said power units comprising motors and concentric epicyclic gear speed reducers, the low speed shaft of each speed reducer carrying one said pinion.

4. In a controllable pitch propeller, a shaft having a. hub secured thereto the hub including blade sockets having blades journalled therein for pitch change, a bevel gear sector on each blade butt, a bevel gear concentric with the hub engaging said gear sectors, a spur gear concentrio with and secured to said bevel gear, power units secured to the hub between said blade sockets each having a driving pinion engaging said spur gear, said power units comprising clec-- tric motors electrically connected in parallel, and slip rings on the propeller hub through which electrical power is selectively fed to said motors to effect joint operation thereof and consequent coincidental pitch change of the propeller blades.

5. In a controllable pitch propeller, a hub having radiating blade sockets, a blade journaled in each socket for pitch change and having a bevel gear sector at the'butt thereof and lying within the hub, a bevel gear concentric with and lying within the hub engaging the several butt sectors for effecting joint pitch change of the blades, a concentric gear secured to the bevel gear having segmental toothed rim portions disposed substantially between said blades, power units secured to the hub substantially in the p ,peller plane of rotation and one unit being disposed between each adjacent pair of propeller blades, and a driving connection from said units to respective gear rim segmental portions.

6. In a controllable pitch propeller, a hub having radiating blade sockets, a blade journaled in each socket for pitch change and having a bevel gear sector at the butt thereof and lying within the hub, a bevel gear concentric with and lying within the hub engaging the several butt sectors for effecting joint pitch changeof the blades,

a concentric gear secured to the bevel gear having segmental toothed rim portions disposed substantially between said blades, power units secured to the hub substantially in the propeller plane of rotation and one unit being disposed between each adjacent pair of propeller blades, a driving connection from said units to respective gear rim segmental portions, a front housing for the propeller hub, and lugs on the housingextending between said rim portions into hub contact to afford an attachment of the housing to the hub.

'l. ,Ina propeller having an odd number of duction gear units being disposed in the plane of said blades, means to supply power to said units, annular means embracing the hub axis and rotatable relative to the hub, and direct,

driving connections between said annular means and the several units and between said annular means and the several blades. r

8. In a propeller hub comprising plural blades adjustable for pitch change, power transmission units radially spaced from the hub axis and disposed between the blades, a drive pinion on each unit, a gear concentric with the hub engaged with said pinions and having segmental cutouts in its web, bosses passing through said cutouts rigid with the hub, and outboard bearings for said pinions carried by said bosses.

9. In a propeller hub comprising plural blades adjustable for pitch change, power transmission units radially spaced from the hub axis and disposed between the blades, a drive pinion on each unit, a gear concentric with the hub engaged with said pinions and having segmental cutouts in its web, bosses passing through said cutouts rigid with the hub, and outboard bearings for said pinions carried by said bosses, said hub and bosses having radially extending webs embracing said gear.

10. In an aircraft propeller, a hub having blade sockets, changeable pitch blades in said sockets each having a bevel gear at its butt, a gear unit concentric with the hub having a bevel gear meshed with the blade butt gears and having a spur gear, a plurality of power transmission units mounted upon the hub between the propeller blades, each said transmission unit having a central axis parallel to and spaced from the hub axis. and an output gear on each transmission unit, coaxial with the transmission unit axis, meshed with said spur gear.

11. In an aircraft propeller, a hub having blade sockets, changeable pitch blades in said sockets each having a bevel gear at its butt, a gear unit concentric with the hub having a bevel gear meshed with the blade butt gears and having aspur gear, a plurality of power transmission units mounted upon the hub between the propeller blades, each said transmission unit having a central axis parallel to and spaced from the hub axis, an output gear on each transmission unit, coaxial with the transmission unit axis, meshed with said spur gear, and means to drive said power transmission units.

12. In an aircraft propeller, a hub having blade sockets, changeable pitch blades in said sockets each having a bevel gear at its butt, a gear unit concentric with the hub having a bevel gear meshed with the blade butt gears and having a spur gear, a plurality of power transmission units mounted upon the hub between the propeller blades, each said transmission unit having a cen-- tral axis parallel to and spaced from the hub axis, an output gear on each transmission unit, 1 coaxial with the transmission unit axis, meshed with said spur gear, each said power transmission unit having a coaxial input element, and means drivably connected to said inputelements.

13. In an aircraft propeller, a hub having blade sockets, changeable pitch blades therein each havspeed and position equalizing means between the I ing a bevel gear at its butt, within the hub, a central bevel gear concentric with and Journalled in the hub engaging said butt gears, said central.

gear having a shaft extending forwardly of the hub, a spur gear on said shaft, a plurality of speed reducer units disposed between the blades on said hub, each having.an output pinion meshed with said spur gearjsaid pinions being axially parallel to the hub, and power means driving said speed reducer units, said spur and central gear being serially connected between said power units and blades and comprising power transmitting,

speed reducer units and between the blades.

14. In a controllable pitch propeller comprising a hub having blades rotatable for pitch change, a plurality of reduction gear umts, each having a high speed input shaft and a coaxial low speed output shaft, said units being spaced around said hub in the plane of said blades, means to drive the high speed input shafts, a low speed gear concentric with the hub driven by the several low speed output shafts, and a low speed driving connection from said low speed gear to each propeller blade. I

15. In a variable pitch dual rotation propeller a rotatable system comprising inboard and outboardpropeller hubs arranged in tandem relation and a drive shaft arrangement therefor, sets of propeller blades carried .by the respective hubs, pitch changing power producing means on and rotatable with each hub of said system each said means being drivably connected with respective sets of propeller blades, one of said pitch changing means comprising a plurality of units spaced around said drive shaft arrangement, a first power transfer means on the inboard hub having parts connected to the pitch changing means of the inboard propeller hub, and second power transfer means between and mounted on the inboard and outboard propeller hubs,'parts of the second power transfer means on the inboard propeller hub being directly connected to parts of the first power transfer means, and parts of the second power transfer means on the outboard propeller hub being connected to the pitch changing means of the outboard propeller hub.

16. In a variable pitch dual rotation propeller a rotatable system comprising inboard and outboard propeller hubs arranged in tandem relation and a drive shaft arrangement therefor, sets of propeller blades carried by the respective hubs, pitch changing power producing means on and rotatable with each hub of said system and respectively connected in driving relation with respective sets of propeller blades, each said pitch changing means comprising a plurality of units spaced symmetrically around said 'drive shaft arrangement, a first power transfer means on the inboard hub having parts thereof connected to the pitch changing means of the inboard hub, and second power transfer means between and mounted on the inboard and'outboard propeller hubs, parts of the second power transfer means on the inboard hub being directly connected to parts f the first power transfer means, and parts of the second power transfer means on the outboard hub being directly connected to the propeller pitch changing means of the outboard hub.

1'7. In a variable pitch dual rotation propeller a rotatable system comprising propeller hubs arranged in tandem relation and a drive shaft ar rangement therefor, sets of propeller blades carried by the respective hubs, independently operable motor means mounted on and rotatable with 7 each propeller hub of said system and connected in driving relation with respective sets of propeller blades for changing the pitch thereof, and means for energizing said motor means separately to change the pitch of said sets of propeller blades independently, the longitudinal axes of 'said individual motor means lying parallel to and spaced from the longitudinal axis of said rotatable system and from the axis of said drive shaft, said energizing means including a first power transfer means on the inboard propeller hub having parts connected to the inboard propeller hub motor means, and second power transfer means between and mounted on the inboard and outboard propeller hubs, parts of the second power transfer means on the inboard propeller hub being directly connected to parts of said first power transfer means, and parts of the second power transfer means on the outboard propeller hub being connected to the outboard propeller hub motor means.

18. In a variable pitch dual rotation propeller comprising coaxial tandem oppositely driven inboard and outboard hubs each having blades rotatable therein for pitch change, a blade pitch changing motor carried by and rotatable with each hub, means drivably connecting each motor to the blades of the corresponding hub, and means for operating said motors independently of one another to effect independent blade pitch change in each of the tandem hubs, said perating means including a first power transfer means on the inboard hub having parts connected to the inboard pitch changing motor, and second power transfer means between and mounted on the inboard and outboard propeller hubs, parts of the second power transfer means on the inboard hub being directly connected to parts of the first power transfer means, and parts of the second power transfer'means on the outboard hub being connected to the outboard pitch changing motor.

MARTHA W. MORRIS. Administratria' of the Estate of Edward W. Morris,

Deceased.

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